Quick question should I get continuity between my ground and TX ( Blue wire )
That looks like a digital serial interface if I am right?
To me it is not normal a TX or RX line having continuity to ground.
Did you measure it in isolation, disconnecting the modules from each other?
And it may sound like a stupid question but…Did you measure it with the thing unpowered?
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Often you do yes… This can depend on how big the pull-down resistance on the output is.
It’s usually more noticeable on the analog VTX input signal line.
What kind of interface is it?
That’s just a UART.
wild pull-downs those
Maybe to minimize EMI effects?
My question would be…
Why are you asking 
Because I want to know
Soz I was asking the op
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What are you asking?
I see you have your profession down as electronics engineer… so i assume you know and are just trying to catch me out. Thats fair.
Whilst I do have an electronics degree, my electronics is now 100% hobby and I am now a professional programmer. I’ve not done professional electronics for 25 years. So forgive me if I’m rather rusty.
Hi Yith.
My intention is learning, so that’s the reason I ask.
Yes, electronics is my profession, but I am completely new to these systems.
The reason I mentioned EMI is because I never saw a pulldown resistor with such low resistance value on a UART line, and EMI mitigation is the only thing I can think of to justify it.
I appreciate everyone’s background and experience. I am the newbbie here.
Have a nice day!
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I’ve no idea if there is a pull-down resistor or not. All I’m saying that depending on how they have implemented it, you might get continuity where you least expect it.
Ok noted.
Thanks
wow 
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@BigDog May I ask what FPV are you using?
03 dude, im way behind the times …
03 dude, im way behind the times…lol… Im all built up and ready for the next stage which I hate “Software”
Just downloader mission planner now and then look to follow some one on YT who knows what they are doing “unlike me”
Ok a lot of confusion around Ardupilot, Iv downloaded mission planner as to setup the Mannta and looked on YT for some tutorials as I have no idea how to use this software.
Came across a guy call Andrew Newton who seems to know his onions, the problem is he is using Qground control to set his up, so am I using the wrong software? Or is he using an older version ?.
Both MP and QGC are current valid options
MP is the full Monty
QGC is cut down as it is primarily used for mobile applications
Ok I feel Im getting somewhere with this, Iv managed to sort my servo’s out as they were the wrong way round, moved the arming to a button rather than the sticks. That said my control surfaces seem to have a find of there own and the start to randomly move, just need to sort my switches out now but this is straight forward as Tango2 switches are letters and Ardu are numbers. Now you would think they correspond accordingly i.e 1 = A 2 = B and so on but no, when I changed my arm switch which was button A in married up to RC5_ ??? …